(中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 通過電子背散射衍射實驗對復(fù)合添加稀土元素Yb和過渡族元素Zr或Cr的Al-Zn-Mg-Cu超高強合金的晶粒尺寸、晶界類型、晶界特性進行研究，分析了微合金化后的晶界特性對合金力學(xué)性能和局部腐蝕(晶間腐蝕和剝落腐蝕)的影響。結(jié)果表明：與復(fù)合添加Yb和Cr相比，復(fù)合添加Yb和Zr的Al-Zn-Mg-Cu合金具有最佳的再結(jié)晶抑制效果；高溫固溶-時效處理后，合金晶粒尺寸由40 μm顯著細化到2.3 μm，再結(jié)晶程度從98%下降到3%，Σ27晶界所占比例大幅提高，小角度晶界所占比例由8%提高到51%；亞晶界上的析出相與晶內(nèi)的析出相近似，合金的力學(xué)性能和耐腐蝕性能顯著提高，使得合金拉伸斷裂時，沿晶斷裂分數(shù)大幅降低，合金的力學(xué)性能和耐腐蝕性能顯著提高。
關(guān)鍵字: 稀土Yb；過渡族元素；電子背散射衍射；力學(xué)性能；腐蝕
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The electron backscatter diffraction (EBSD) experiments were conducted to study the grain size, grain boundary types and feature in Al-Zn-Mg-Cu super high-strength alloys by complex additions of rare earth element Yb and transition element Zr or Cr. The effect of grain boundary character on the mechanical properties and localized corrosion (Intergranular corrosion and exfoliation corrosion) of Al-Zn-Mg-Cu alloy was investigated. The results show that, comparing with Yb and Cr addition, the recrystallization of Al matrix can be strongly inhibited by complex additions of Yb and Zr to Al-Zn-Mg-Cu alloy. After high temperature solution-T6 temper, the average grain size and recrystallized volume fraction decrease from 40 μm and 98% to 2.3 μm and 3%, respectively. The Σ27 accounted for the highest proportion of grain boundaries, the proportion of small-angle grain boundaries increases from 8% to 51%. The precipitates on the subgrain boundaries are similar with those in the grain, leading to the decrease of the volume fraction of fracture along recrystallized grain, and the mechanical properties and resistance to corrosion of the alloys increase sharply.
Key words: rare earth Yb; transition element; electron backscatter diffraction; mechanical property; corrosion
